Current Medicare policy unnecessarily limits the mobility of the frail elderly by funding purchases of inappropriate manual wheelchairs. The long term, far reaching goal of this research proposal is to alter Medicare policy such that the mobility of the frail elderly is improved through purchases of ultralight manual wheelchairs and/or power wheelchairs. Specifically, we are investigating the effect of rear axle position, wheelchair weight, and surface rolling resistance on the biomechanics of wheelchair propulsion in the frail and non-frail elderly. Elderly frail and non frail individuals, as defined by the presence of 3 of 5 criteria, will propel in four wheelchair configurations (2 axle positions and 2 weight conditions) across four surfaces with increasing varied rolling resistance. Participants will also complete a six minute wheel and isometric wheelchair push as measures of functional performance. Outcome variables of interest include cadence, self-selected velocity, RPE, resultant force, effective force, maximal force (isometric test), and total distance traveled (6 min. wheel). In general we hypothesize that frail elderly individuals will have larger differences in propulsion biomechanics in response to the different wheelchair configurations than the non-frail group.